Image forming method

Abstract

Provided is an image forming method that achieves both quick drying of ink and suppression of swelling of a resin portion inside a head. The present invention is a method of forming an image by discharging ink from an inkjet head. The inkjet head has an ink flow path and a resin portion that is at least partially exposed in the ink flow path, and the resin portion includes a cured product of a composition containing an episulfide resin and a polythiol compound. The ink contains an alcohol having 1 to 4 carbon atoms in an amount of 60% by mass or more and 95% by mass or less based on the total mass of the ink.

Description

Technical Field

[0001] The present invention relates to an image forming method.

Background Art

[0002] The inkjet method can form images on various substrates including paper and film, and thus is widely used. On the other hand, when forming an image on a non-absorbent substrate such as film, if the applied ink dries insufficiently, the image may fade or transfer due to contact with other substrates, resulting in a decrease in image quality. Therefore, fast-drying ink is required.

[0003] For fast-drying ink, highly volatile ketones and alcohols are used as solvents. For example, Patent Document 1 describes ink with enhanced fast-drying properties using methyl ethyl ketone. Also, Patent Document 2 describes ink with enhanced fast-drying properties using lower carbon alcohols.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described in Patent Document 2, an ink with enhanced quick-drying properties using alcohol is known. However, alcohol has high permeability into resins. Therefore, when attempting to form an image by an inkjet method using such an ink, there has been a problem that the ink penetrates into the resin part inside the inkjet head and the resin part swells. For example, when the adhesive swells, deformation of the head may occur, or stress may locally concentrate and peeling may occur, resulting in defects such as nozzle defects.

[0006] The present invention has been made in view of the above problems. An object of the present invention is to provide an image forming method that achieves both quick-drying properties of the ink and suppression of swelling of the resin part inside the head.

Means for Solving the Problems

[0007] One aspect of the present invention for solving the above problems relates to the image forming methods of the following [1] to

[13] . [1] A method of forming an image by discharging ink from an inkjet head, The inkjet head has an ink flow path and a resin part at least partially exposed in the ink flow path, The resin part includes a cured product of a composition containing an episulfide resin and a polythiol compound, The ink contains an alcohol having 1 to 4 carbon atoms in an amount of 60% by mass or more and 95% by mass or less based on the total mass of the ink, Image forming method. [2] The ink contains ethanol in an amount of 30% by mass or more based on the total mass of the ink, The image forming method according to [1]. [3] The resin part is a cured product of a composition further containing a curing catalyst, The image forming method according to [1] or [2]. [4] The curing catalyst contains an amine or an imidazole, The image forming method according to [3]. [5] The cured product has an impregnation rate calculated by the following formula (1) of less than 4.0% based on the mass when performing TGA measurement in which, after being immersed in 100% ethanol at 60°C for 2 weeks, the sample temperature is raised from 30°C to 100°C at a rate of 7°C / min and then held for 1 hour. The image forming method according to claim 1. Impregnation rate (%) = (Mass before TGA heating - Mass after TGA heating) / (Mass before TGA heating) × 100 (1) [6] The polythiol compound is a compound having 4 or more thiol groups. The image forming method according to any one of [1] to [5]. [7] The resin part is a joint part that joins the diaphragm and the pressure chamber forming substrate. The image forming method according to any one of [1] to [6]. [8] The resin part has a thickness of 0.1 μm or more and 2.5 μm or less. The image forming method according to [7]. [9] The resin part is a joint part that joins the nozzle plate and the pressure chamber forming substrate. The image forming method according to any one of [1] to [8].

[10] The resin part has a thickness of 0.5 μm or more and 4.0 μm or less. The image forming method according to [9].

[11] The inkjet head circulates the ink for each nozzle that discharges the ink. The image forming method according to any one of [1] to

[10] .

[12] When the inkjet head does not discharge the ink, the ink is caused to flow by a shaking waveform. The image forming method according to any one of [1] to

[11] .

[13] An image is formed on a recording medium conveyed by roll-to-roll. The image forming method according to any one of [1] to

[12] .

Advantages of the Invention

[0008] According to the present invention, it is possible to provide an image forming method that achieves both quick-drying property of ink and suppression of swelling of the resin portion inside the head.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0011] The present embodiment relates to a method of forming an image using an inkjet head using a specific cured product for the resin portion and an ink having a high alcohol concentration. Hereinafter, an inkjet printer having the inkjet head and the ink will be described.

[0012] [Inkjet Printer 1] FIG. 1 is a diagram showing a schematic configuration of an inkjet printer used for forming an image in the present embodiment, and FIG. 2 is a block diagram showing a main part of a control system of the inkjet printer. The inkjet printer described below is an example of an image forming apparatus.

[0013] As shown in FIGS. 1 and 2, the inkjet printer 1 includes a conveyance unit 10, a supply unit 20, a discharge unit 30, an ink supply unit 40, a drawing unit 50, a drying unit 95, a reading unit 60, an operation display unit 70, an input / output interface 80, a control unit 90, and the like.

[0014] The conveyance unit 10 has a plurality of members related to conveyance, such as a conveyance belt 11, a drive roller 12, and a driven roller 13. The conveyance unit 10 conveys the recording medium M by the conveyance operations of a plurality of members such as the conveyance belt 11. Specifically, in the conveyance unit 10, the conveyance belt 11 is stretched between the drive roller 12 and the driven roller 13 and is driven by rotationally driving the drive roller 12. As a result, the recording medium M supplied from the supply unit 20 is conveyed to the drawing unit 50 while being placed on the conveyance surface 11a of the conveyance belt 11, and after being drawn (also referred to as image formation or printing) by the drawing unit 50, it is conveyed to the discharge unit 30. In this way, the inkjet printer 1 forms an image in a roll-to-roll manner.

[0015] As the recording medium M, various media capable of fixing the ink ejected from the inkjet head 55 can be used. The recording medium M is, for example, a roll-shaped resin (film). Note that the recording medium M is not limited to a film, and may be a sheet-like paper, cloth, or the like. Also, the recording medium M is not limited to a roll-shaped medium, and may be a medium such as a sheet-like paper, cloth, or resin. An example of the resin-made recording medium M includes a PET film for food packaging. Examples of other recording media M that can be a drawing target include a metal body of an automobile, building materials (outer walls, roofing materials, tiles, etc.), and cans (metal cans for containing food, beverages, etc.).

[0016] FIG. 1 illustrates a transport unit 10 that transports a recording medium M by a transport belt 11 as an example of an image forming apparatus. However, the transport unit 10 is not limited to the transport belt 11, and may be configured to transport the recording medium M by a drum or a roller.

[0017] The supply unit 20 includes a storage unit 21 that stores the recording medium M stored in a roll shape, and a pay-out roller 22 that feeds out and supplies the recording medium M from the storage unit 21 to the transport unit 10.

[0018] The discharge unit 30 includes a storage unit 31 that stores and accommodates the recording medium M in a roll shape, and a take-up roller 32 that transports the recording medium M transported from the transport unit 10 to the storage unit 31.

[0019] The pay-out roller 22 and the take-up roller 32 have, for example, a plurality of rollers, and transport the recording medium M by rotating the rollers.

[0020] Note that the configurations of the transport unit 10, the supply unit 20, and the discharge unit 30 can be variously changed and implemented according to the type of the recording medium M to be drawn.

[0021] The ink supply unit 40 is a device that supplies ink to a first sub-tank 52a of a drawing unit 50 described later. The ink supply unit 40 includes a main tank 41 and members related to ink supply (e.g., a pump, a valve, etc., not shown). The main tank 41 stores the ink to be supplied to the first sub-tank 52a at room temperature. The ink supply unit 40 supplies the ink from the main tank 41 to the first sub-tank 52a through a flow path 42 using a pump or the like (not shown).

[0022] The drawing unit 50 includes a carriage 51, a first sub-tank 52a, a second sub-tank 52b, flow paths 53a, 53b, 53c, a head drive unit 54, an inkjet head 55, etc. (see FIGS. 1 and 2). In the present embodiment, the drawing unit 50 forms an image by applying ink (referred to as high alcohol concentration ink) containing 60% by mass or more and 95% by mass or less of an alcohol having 1 to 4 carbon atoms to the recording medium M.

[0023] In FIG. 1, for the sake of simplicity, only one ink supply unit 40 and one drawing unit 50 for one color are illustrated. However, the ink supply unit 40 and the drawing unit 50 are arranged according to the number of colors used. For example, when using four colors of yellow (Y), magenta (M), cyan (C), and black (K), four ink supply units 40 and four drawing units 50 are arranged, and the drawing units 50 are arranged at predetermined intervals along the transport direction T.

[0024] Also, a plurality of second sub-tanks 52b and heads 55 are connected downstream of the first sub-tank 52a. However, in FIG. 1, for the sake of simplicity, only one of each is illustrated.

[0025] The carriage 51 is a housing that holds inside the first sub-tank 52a, the second sub-tank 52b, the flow paths 53a, 53b, 53c, the head driving unit 54, the head 55, and other devices and members necessary for image formation. Also, although not shown, the carriage 51 may have an ink heating unit that heats and maintains the ink inside the carriage 51.

[0026] The first sub-tank 52a is connected downstream of the main tank 41. The first sub-tank 52a stores the ink supplied from the main tank 41 inside the carriage 51. The ink in the sub-tank 52 is supplied to the second sub-tank 52b through the flow path 53a using a pump or the like (not shown) inside the carriage 51.

[0027] A plurality of second sub-tanks 52b are connected downstream of the first sub-tank 52a. The second sub-tank 52b stores the ink supplied from the first sub-tank 52a within the carriage 51. The ink within the second sub-tank 52b is supplied to a manifold 56 of a head 55 described later via a flow path 53b using a pump or the like (not shown) within the carriage 51. Also, a part of the ink supplied to the manifold 56 is circulated (recovered) to the second sub-tank 52b via a flow path 53c, enabling re-supply to the manifold 56. That is, the ink circulates between the second sub-tank 52b and the manifold 56 via the flow paths 53b and 53c.

[0028] Based on the control of a control unit 90 described later, the head drive unit 54 outputs a drive voltage corresponding to the image data of the image to be formed to a piezoelectric element 58 of a head 55 described later. Due to the drive voltage from the head drive unit 54, the piezoelectric element 58 is driven, and an amount of ink corresponding to the image data is ejected from a nozzle 59 of the head 55 described later. Note that the head drive unit 54 may output a drive voltage corresponding to a wobbling waveform for slightly flowing and stabilizing the ink in the nozzle when the ink is not being ejected to the piezoelectric element 58.

[0029] Note that the wobbling waveform is a waveform that contracts or expands the volume of the pressure chamber 57 within a range where only a pressure wave is generated without ejection. By wobbling the interface of the ink near the nozzle 59 with the wobbling waveform, clogging (de-capping) due to the ink drying and increasing in viscosity can be suppressed.

[0030] A plurality of heads 55 are connected downstream of each of the plurality of second sub-tanks 52b. That is, the second sub-tanks 52b and the heads 55 are connected downstream of the first sub-tank 52a in plurality.

[0031] The head 55 has a manifold 56, a pressure chamber 57, a piezoelectric element 58, a nozzle 59, and a common supply passage 112a, an individual supply passage 112b, a vertical supply passage 112c, a common discharge passage 112d, an individual discharge passage 112e, and a vertical discharge passage 112f (see FIGS. 5A, 5B, and 6), etc. The head 55 has a plurality of nozzles 59, and the pressure chambers 57 and the piezoelectric elements 58 are respectively provided according to the number of the nozzles 59.

[0032] The manifold 56 communicates with a plurality of pressure chambers 57 via each supply passage, and the ink supplied to the manifold 56 is supplied to the pressure chambers 57. The pressure chamber 57 is a chamber having an internal space in which part or all of the ink discharged from the nozzle 59 can be temporarily stored. A piezoelectric element 58 is disposed above the pressure chamber 57. One end of the nozzle 59 communicates with the pressure chamber 57, and the other end is an open end.

[0033] A drive voltage from the head drive unit 54 is applied to the piezoelectric element 58. When a drive voltage from the head drive unit 54 is applied to the piezoelectric element 58, the piezoelectric element 58 deforms according to the applied drive voltage, the pressure chamber 57 deforms, and the deformation of the pressure chamber 57 gives a pressure change to the ink in the pressure chamber 57 supplied to the nozzle 59.

[0034] Therefore, when a drive voltage from the head drive unit 54 is applied to the piezoelectric element 58, the piezoelectric element 58 and the pressure chamber 57 deform to give a pressure change to the ink in the pressure chamber 57. As a result, the ink in the pressure chamber 57 is discharged from the nozzle 59. In this way, an image can be formed on the recording medium M by discharging the ink from the nozzle 59.

[0035] In the carriage 51, the head 55 may be configured to be a single-pass system that performs image formation in one scan, or may be configured to be a scan (multi-pass) system that performs image formation in multiple scans. In the case of the single-pass system, in the width direction of the recording medium M (the direction orthogonal to the conveyance direction T of the recording medium M), the number of heads 55 corresponding to the image formation width is arranged on the carriage 51 (see FIG. 3). As shown in FIG. 3, the plurality of heads 55 are arranged in one or a plurality of rows with their longitudinal directions along the width direction of the recording medium M. In each head 55, the plurality of nozzles 59 are arranged linearly or in a grid pattern along the longitudinal direction of the head 55.

[0036] The drying unit 95 is arranged on the downstream side of the drawing unit 50 in the conveyance direction T of the recording medium M, and heats and dries the ink applied to the recording medium M. The drying unit 95 is connected to the control unit 90 (see FIG. 2) and is controlled by the control unit 90.

[0037] For example, the drying unit 95 has an infrared heater or the like, and based on a control signal supplied from the control unit 90, power is supplied to the infrared heater, causing the infrared heater to generate heat and dry the ink. The heating conditions by the drying unit 95 may be any conditions under which the high-alcohol-concentration ink dries. Also, when the drying property of the ink is sufficient, the inkjet printer 1 may not have the drying unit 95.

[0038] The reading unit 60 is arranged on the downstream side of the drawing unit 50 and the drying unit 95 in the conveyance direction T of the recording medium M, and reads an image (for example, a predetermined pattern image) formed on the recording medium M conveyed by the conveyance belt 11. The reading unit 60 outputs the reading result of the predetermined pattern image to the control unit 90. The control unit 90 changes the image formation conditions, such as the image formation position and the driving conditions of the head 55, based on the reading result.

[0039] Also, although not shown, the inkjet printer 1 includes a maintenance unit that performs maintenance such as cleaning of the head 55.

[0040] The operation display unit 70 is, for example, a flat panel display such as a liquid crystal with a touch panel or an organic EL (Electro Luminescence). The operation display unit 70 displays an operation menu for the user, information regarding image data, various states of the inkjet printer 1, and the like. Further, the operation display unit 70 includes a plurality of keys and accepts various input operations by the user.

[0041] The input / output interface 80 mediates the transmission and reception of data between the external device 99 and the control unit 90. The input / output interface 80 is configured by, for example, any one of various serial interfaces, various parallel interfaces, or a combination thereof.

[0042] The external device 99 is, for example, a personal computer, a facsimile device, or the like, and supplies a print job, image data, and the like to the control unit 90 via the input / output interface 80.

[0043] The control unit 90 includes a CPU (Central Processing Unit) 91, a RAM (Random Access Memory) 92, a ROM (Read Only Memory) 93, a storage unit 94, and the like.

[0044] The CPU 91 reads out various control programs and setting data stored in the ROM 93, stores them in the RAM 92, and executes the programs to perform various arithmetic processes. For example, the control unit 90 generates a drive signal for the image to be formed based on the image data received from the input / output interface 80 and outputs it to the head 55.

[0045] The RAM 92 provides a working memory space for the CPU 91 and stores temporary data. Note that the RAM 92 may include a non-volatile memory.

[0046] The ROM 93 stores various control programs, setting data, etc. to be executed by the CPU 91. Note that instead of the ROM 93, a rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

[0047] In the storage unit 94, print jobs input from the external device 99 and image data related to the print jobs are stored via the input / output interface 80. As the storage unit 94, for example, a non-volatile semiconductor memory (so-called flash memory) or an HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) etc. may be used in combination.

[0048] To the control unit 90, a conveyance unit 10, a supply unit 20, a discharge unit 30, an ink supply unit 40, a drawing unit 50, a reading unit 60, an operation display unit 70, an input / output interface 80, a drying unit 95, etc. are respectively connected. The control unit 90 overall controls the entire operation of the inkjet printer 1. The conveyance unit 10, the supply unit 20, the discharge unit 30, the ink supply unit 40, the drawing unit 50, the reading unit 60, the operation display unit 70, the input / output interface 80, the drying unit 95, etc. are controlled by the control unit 90 to execute predetermined processes.

[0049] The inkjet printer 1 having the above configuration supplies the recording medium M from the supply unit 20 to the conveyance unit 10 under the control of the control unit 90, performs drawing on the recording medium M conveyed to the conveyance unit 10 by the drawing unit 50, and conveys the recording medium M on which an image is formed to the discharge unit 30.

[0050] [Head (Inkjet Head) 55] Next, the configuration of the inkjet head (head 55) according to the present embodiment will be described. The configuration described here is the configuration of the head 55 alone. Note that the configurations of all the heads 55 in the inkjet printer 1 may be the same, or the inkjet printer 1 may include a head 55 having a configuration different from the configuration described below.

[0051] FIG. 4 is a perspective view showing the appearance of the head 55.

[0052] The head 55 includes a housing 101 and an exterior member 102 that fits with the housing 101 at the lower end of the housing 101, and main components are housed inside the housing 101 and the exterior member 102. Among these, the exterior member 102 is provided with an inlet 103a through which ink is supplied from the outside, and outlets 103b and 103c through which the ink is discharged to the outside. Further, a manifold 56 connected to the inlet 103a is provided inside the exterior member 102. In addition, the exterior member 102 is provided with a plurality of mounting holes 104 for attaching the inkjet head 55 to the base of the carriage 51.

[0053] FIGS. 5A and 5B are diagrams showing the main configuration of the head chip in the head 55. FIG. 5A is a diagram schematically showing the main configuration of a cross-section along the short side direction of the head chip, and FIG. 5B is a diagram schematically showing the main configuration of a cross-section along the long side direction of the head chip. FIG. 6 is a diagram schematically showing the cross-sectional configuration of the pressure chamber forming plate 112 in the head 55.

[0054] The components housed inside the housing 101 and the exterior member 102 of the head 55 include a head chip 110. As shown in FIGS. 5A and 5B, the head chip 110 is configured by laminating a plurality of substrates (the nozzle plate 111, the pressure chamber forming plate 112 (pressure chamber forming substrate), the drive plate 113, and the housing portion 114 in this order) and bonding them.

[0055] The nozzle plate 111 is provided with a plurality of nozzles 59 (discharge holes), which are holes penetrating in the thickness direction (corresponding to the ink discharge direction. The ink discharge direction typically follows the vertical direction), arranged in a row along the longitudinal direction.

[0056] On the surface of the nozzle plate 111 on the ink discharge side, a liquid-repellent film 111a is formed. The material contained in the liquid-repellent film 111a is not particularly limited, but for example, it is a fluororesin. Also, the thickness of the liquid-repellent film 111a is not particularly limited, but for example, it is 1 nm or more and less than 100 nm.

[0057] The pressure chamber forming plate 112 is provided with a plurality of pressure chambers 57, which are holes penetrating in the thickness direction and each communicating with a corresponding nozzle 59, arranged in a row along the longitudinal direction (see Fig. 6). Further, the pressure chamber forming plate 112 is provided with a common supply flow path 112a provided on one side along the row of the pressure chambers 57, and individual supply flow paths 112b. Also, the pressure chamber forming plate 112 is provided with a common discharge flow path 112d provided on the other side along the row of the pressure chambers 57, and individual discharge flow paths 112e. At the tip of the common supply flow path 112a, a vertical supply flow path 112c communicating with the manifold 56 is provided. At the tip of the common discharge flow path 112d, a vertical discharge flow path 112f communicating with the outlet 103c is provided.

[0058] All of the plurality of pressure chambers 57 are partitioned by a partition wall 57a. Also, the pressure chambers and the common supply flow path 112a and the common discharge flow path 112d are partitioned by a partition wall 57b. The partition wall 57a and the partition wall 57b are entirely formed of a metal such as nickel (Ni) that can be electroplated. Thereby, the rigidity of the partition wall 57a can be increased, making the head 55 less likely to be damaged by vibration and having a stable structure.

[0059] The common supply channel 112a allows the ink supplied from the manifold 56 via the vertical supply channel 112c to flow through. The individual supply channels 112b are provided for each pressure chamber 57 and supply the ink flowing through the common supply channel 112a to the respective pressure chambers 57. The individual discharge channels 112e are provided for each pressure chamber 57 and discharge the ink that has not been ejected from the pressure chamber 57 to the common discharge channel 112d. The common discharge channel 112d guides the ink discharged from the pressure chamber to the outlet 103c via the vertical discharge channel 127f. In this way, each channel enables the circulation of ink for each nozzle 59 that ejects ink.

[0060] The drive plate 113 has a diaphragm 57c provided on the lower surface (the surface on the side of the pressure chamber forming plate 112) and a space portion 113a disposed at a position facing the pressure chamber 57 with the diaphragm 57c interposed therebetween. A piezoelectric element 58 is housed in the space portion 113a. The piezoelectric elements 58 are arranged for each pressure chamber 57 (for each nozzle 59) at positions facing the pressure chamber 57 with the diaphragm 57c interposed therebetween.

[0061] The piezoelectric element 58 is electrically connected to the head drive unit 54 by electrodes and wiring (not shown). The piezoelectric element 58 is driven in response to a drive voltage signal applied from the head drive unit 54 via the electrodes and wiring, causing repeated push-mode displacements in the diaphragm 57c and the pressure chamber 57, thereby varying the pressure of the ink. In response to this pressure variation, the ink is ejected from the nozzle 59. That is, the head 55 according to the present embodiment is an inkjet head that performs push-mode ink ejection. Note that the present embodiment is not limited to a push-mode head, and as long as it has a resin portion including the materials described later, it may be another piezo-type head such as a bend mode or a shear mode, or a thermal head.

[0062] Note that the positions of the diaphragm 57c and the piezoelectric element 58 are not limited to the positions shown in FIGS. 5A and 5B. For example, the diaphragm 57c may be disposed on the surface of the pressure chamber 57 on the nozzle 59 side, and the piezoelectric element 58 may be disposed on the nozzle 59 side of the diaphragm 57c. Further, the diaphragm 57c may be disposed along the ink flow direction on the side wall of the pressure chamber 57, and the piezoelectric element 58 may be disposed inside the partition wall 57a. As long as the pressure chamber can be contracted or expanded, the diaphragm 57c and the piezoelectric element 58 may be disposed at any position.

[0063] The drive plate 113 is provided with a vertical supply channel 113c and a vertical discharge channel 113f. The most downstream part of the vertical supply channel 113c communicates with the vertical supply channel 112c. The vertical discharge channel 113f communicates with the outlet 103c.

[0064] The materials of the nozzle plate 111, the pressure chamber forming plate 112, and the drive plate 113 are not particularly limited, and known materials such as silicon (Si), nickel (Ni), stainless steel, and polyimide can be used.

[0065] The housing portion 114 is provided with a manifold 56 that extends along the longitudinal direction of the head 55 and communicates with all of the plurality of pressure chambers 57 at the most upstream portion. The housing portion 114 may be a resin substrate such as polyimide, or a metal substrate such as SUS.

[0066] FIG. 7 is a diagram schematically showing a main part configuration of a cross section in the vicinity of the pressure chamber 57 in the inkjet head 55 of the present embodiment. For ease of understanding, the scale in the vertical direction of the paper surface is enlarged in FIG. 7.

[0067] In the present embodiment, the nozzle plate 111 and the pressure chamber forming plate 112 are adhered by an adhesive layer 210 (one aspect of the resin portion). Further, the pressure chamber forming plate 112 and the drive plate 113 are adhered by an adhesive layer 220 (one aspect of the resin portion). These adhesive layers are at least partially exposed to the ink flow path (here, the pressure chamber 57).

[0068] [Resin part] These resin parts include cured products of compositions containing episulfide resins and polythiol compounds.

[0069] (Episulfide resin) The episulfide resin is a compound having an episulfide ring. The episulfide resin may be a chain aliphatic episulfide resin, an alicyclic episulfide resin, or an aromatic episulfide resin. Only one kind of episulfide resin may be used, or two or more kinds may be used in combination.

[0070] Examples of the chain aliphatic episulfide resin include bis(2,3-epithiopropyl) sulfide, bis(2,3-epithiopropylthio) methane, 1,2-bis(2,3-epithiopropylthio) ethane, 1,2-bis(2,3-epithiopropylthio) propane, 1,3-bis(2,3-epithiopropylthio) propane, 1,3-bis(2,3-epithiopropylthio)-2-methylpropane, 1,4-bis(2,3-epithiopropylthio) butane, 1,4-bis(2,3-epithiopropylthio)-2-methylbutane, 1,3-bis(2,3-epithiopropylthio) butane, 1,5-bis(2,3-epithiopropylthio) pentane, 1,5-bis(2,3-epithiopropylthio)-2-methylpentane, 1,5-bis(2,3-epithiopropylthio)-3-thiapentane, 1,6-bis(2,3-epithiopropylthio) hexane, 1,6-bis(2,3-epithiopropylthio)-2-methylhexane, 3,8-bis(2,3-epithiopropylthio)-3,6-trithiaoctane, 1,2,3-tris(2,3-epithiopropylthio) propane, 2,2-bis(2,3-epithiopropylthio)-1,3-bis(2,3-epithiopropylthiomethyl) propane, 2,2-bis(2,3-epithiopropylthiomethyl)-1-(2,3-epithiopropylthio) butane, 1,5-bis(2,3-epithiopropylthio)-2-(2,3-epithiopropylthiomethyl)-3-thiapentane, 1,5-bis(2,3-epithiopropylthio)-2,4-bis(2,3-epithiopropylthiomethyl)-3-thiapentane, 1-(2,3-epithiopropylthio)-2,2-bis(2,3-epithiopropylthiomethyl)-4-thiahexane, 1,5,6-tris(2,3-epithiopropylthio)-4-(2,3-epithiopropylthiomethyl)-3-thiahexane, 1,8-bis(2,3-epithiopropylthio)-4-(2,3-epithiopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(2,3-epithiopropylthio)-4,5-bis(2,3-epithiopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(2,3-epithiopropylthio)-4,4-bis(2,3-epithiopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(2,3-Epithiopropylthio)-2,5-bis(2,3-epithiopropylthiomethyl)-3,6-dithiaoctane, 1,8-bis(2,3-epithiopropylthio)-2,4,5-tris(2,3-epithiopropylthiomethyl)-3,6-dithiaoctane, 1,1,1-tris[{2-(2,3-epithiopropylthio)ethyl}thiomethyl]-2-(2,3-epithiopropylthio)ethane, 1,1,2,2-tetrakis[{2-(2,3-epithiopropylthio)ethyl}thiomethyl]ethane, 1,11-bis(2,3-epithiopropylthio)-4,8-bis(2,3-epithiopropylthiomethyl)-3,6,9-trithiaundecane, 1,11-bis(2,3-epithiopropylthio)-4,7-bis(2,3-epithiopropylthiomethyl)-3,6,9-trithiaundecane, 1,11-bis(2,3-epithiopropylthio)-5,7-bis(2,3-epithiopropylthiomethyl)-3,6,9-trithiaundecane, etc. are included.,

[0071] Examples of alicyclic episulfide resins include 1,3-bis(2,3-epithiopropylthio)cyclohexane, 1,4-bis(2,3-epithiopropylthio)cyclohexane, 1,3-bis(2,3-epithiopropylthiomethyl)cyclohexane, 1,4-bis(2,3-epithiopropylthiomethyl)cyclohexane, 2,5-bis(2,3-epithiopropylthiomethyl)-1,4-dithiane, 2,5-bis[{2-(2,3-epithiopropylthio)ethyl}thiomethyl]-1,4-dithiane, 2,5-bis(2,3-epithiopropylthiomethyl)-2,5-dimethyl-1,4-dithiane, 2,2-bis(4-(2,3-epithiopropoxy)cyclohexyl)propane, bis(4-(2,3-epithiopropoxy)cyclohexyl)methane, 4,8-bis(4-(2,3-epithiopropoxymethyl)-tricyclo[5.2.1.02.6]decane, 3,9-bis(4-(2,3-epithiopropoxymethyl)-tricyclo[5.2.1.02.6]decane, 3,8-bis(4-(2,3-epithiopropoxymethyl)-tricyclo[5.2.1.02.6]decane, 4,8-bis(4-(2,3-epithiopropoxy)-tricyclo[5.2.1.02.6]decane, 3,9-bis(4-(2,3-epithiopropoxy)-tricyclo[5.2.1.02.6]decane, 3,8-bis(4-(2,3-epithiopropoxy)-tricyclo[5.2.1.02.6]decane, 1,1,1-tris-(4-(2,3-epithiopropoxy)cyclohexyl)ethane, 1-(2-(2,3-epithiopropoxy)cyclohexyl)-1,1-bis-(4-(2,3-epithiopropoxy)cyclohexyl)ethane, 1,1,2,2-tetrakis-(4-(2,3-epithiopropoxy)cyclohexyl)ethane, and the like.

[0072] Examples of the aromatic episulfide resin include 1,2-bis(2,3-epithiopropylthio)benzene, 1,3-bis(2,3-epithiopropylthio)benzene, 1,4-bis(2,3-epithiopropylthio)benzene, 1,2-bis(2,3-epithiopropylthiomethyl)benzene, 1,3-bis(2,3-epithiopropylthiomethyl)benzene, 1,4-bis(2,3-epithiopropylthiomethyl)benzene, bis{4-(2,3-epithiopropylthio)phenyl}methane, 2,2-bis{4-(2,3-epithiopropylthio)phenyl}propane, bis{4-(2,3-epithiopropylthio)phenyl}sulfide, bis{4-(2,3-epithiopropylthio)phenyl}sulfone, 4,4'-bis(2,3-epithiopropylthio)biphenyl, and the like.

[0073] From the viewpoint of more effectively suppressing the swelling of the resin part by the high alcohol concentration ink, alicyclic episulfide resins and aromatic episulfide resins are preferred.

[0074] (Epoxy resin) An episulfide resin and an epoxy resin may be used in combination in the resin part. Only one type of epoxy resin may be used, or two or more types may be used in combination.

[0075] From the viewpoint of enhancing the heat resistance, chemical resistance, swelling resistance, and durability of the resin part, the epoxy resin preferably contains a polyepoxy compound (referred to as epoxy compound A) having an epoxy equivalent of 110 g / eq or less and having three or more epoxy groups. This polyepoxy compound preferably has an epoxy equivalent of 80 g / eq or more and 105 g / eq or less, and more preferably 90 g / eq or more and 100 g / eq or less. Further, this polyepoxy compound preferably has three or more and six or less epoxy groups, and more preferably three or more and four or less epoxy groups.

[0076] Examples of the above polyepoxy compound include compounds represented by formulas (1) to (5).

[0077] [Chemical formula]

[0078] In formula (1), R 1 represents a methyl group, an ethyl group, a propyl group or an isopropyl group. s represents an integer from 0 to 4.

[0079] [Chemical formula]

[0080] In formula (2), R 2 and R 3 each independently represent a methyl group, an ethyl group, a propyl group or an isopropyl group. R 4 represents a methylene group, an ethylidene group or an isopropylidene group. t and u each independently represent an integer from 0 to 4.

[0081] [Chemical formula]

[0082] In formula (3), R 5 represents a methyl group, an ethyl group, a propyl group or an isopropyl group. p represents an integer from 0 to 4.

[0083] [Chemical formula]

[0084] In formula (4), R 6 represents a methyl group, an ethyl group, a propyl group or an isopropyl group. q represents an integer from 0 to 4.

[0085] [Chemical formula]

[0086] From the viewpoint of achieving a good balance between the ease of manufacturing the resin part and adhesion, the resin part preferably further contains, as an epoxy resin, a compound represented by the formula (6) (referred to as epoxy compound B).

[0087]

Chemical formula

[0088] In formula (6), R 7 and R 8 each independently represent a hydrogen atom or a methyl group.

[0089] From the viewpoint of achieving a good balance between the ease of manufacturing the resin part and adhesion, the resin part preferably further contains, as an epoxy resin, a compound represented by the formula (7) (referred to as epoxy compound C).

[0090]

Chemical formula

[0091] In formula (7), r each independently represents 0, 1, or 2. m represents an integer from 0 to 50. R 9 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. A 3 each independently represents any of the divalent linking groups represented by the formula (8).

[0092]

Chemical formula

[0093] In formula (8), * represents the bonding site. R 10 and R 11 each independently represent a hydrogen atom or an unsubstituted or fluorine-substituted methyl group. n represents an integer from 4 to 12.

[0094] When the compound represented by the formula (7) is R 9Examples of alkyl groups that can be used include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a t-butyl group.

[0095] From the viewpoint of more effectively suppressing the swelling of the resin part by the high-alcohol-concentration ink, the compound represented by the formula (7) is preferably the compound represented by the formula (9).

[0096] [Chemical formula]

[0097] Note that the resin part may be a cured product of a composition containing other epoxy compounds. Examples of other epoxy compounds include polyglycidyl ether compounds of mononuclear polyhydric phenol compounds such as hydroquinone, resorcinol, pyrocatechol, and phloroglucinol; polyglycidyl ethers of polyhydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, hexanediol, polyglycol, thiodiglycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, and bisphenol A-alkylene oxide adducts; glycidyl esters of aliphatic, aromatic, or alicyclic polybasic acids such as maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, suberic acid, adipic acid, azelaic acid, sebacic acid, dimer acid, trimer acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and endomethylenetetrahydrophthalic acid; homopolymers or copolymers of glycidyl methacrylate; epoxidized products of cyclic olefin compounds such as vinylcyclohexene diepoxide, dicyclopentadiene diepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-6-methylcyclohexanecarboxylate, and bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate; and epoxidized conjugated diene polymers such as epoxidized polybutadiene and epoxidized styrene-butadiene copolymer, and heterocyclic compounds such as triglycidyl isocyanurate. The epoxy compound may be internally crosslinked by a prepolymer of terminal isocyanate or may be polymerized to a high molecular weight using a polyvalent active hydrogen compound. Examples of the above active hydrogen compounds include polyhydric phenols, polyamines, carbonyl group-containing compounds, and polyphosphoric acid esters.

[0098] From the viewpoint of more effectively suppressing the swelling of the resin part by the high alcohol concentration ink, it is preferable that the content of the epoxy compound A in the above composition is 5% by mass or more, and more preferably 10% by mass or more and 90% by mass or less.

[0099] From the viewpoint of achieving a good balance between the ease of manufacturing the resin part and adhesiveness, the content of the epoxy compound B in the above composition is preferably 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 10% by mass or less.

[0100] From the viewpoint of more effectively suppressing the swelling of the resin part by the high-alcohol-concentration ink and, on the other hand, enhancing the ease of manufacturing the resin part, the content of the epoxy compound C in the above composition is preferably 5% by mass or more and 80% by mass or less, and more preferably 10% by mass or more and 50% by mass or less.

[0101] (Polythiol compound) The polythiol compound acts as a curing agent for the episulfide compound and the epoxy compound. Examples of the polythiol compound include aliphatic polythiol compounds, aromatic polythiol compounds, polythiol compounds having an ether bond, polythiol compounds having an ester bond, and the like. These polythiol compounds may be those addition-modified with an epoxy compound. Only one type of polythiol compound may be used, or two or more types may be used in combination.

[0102] Examples of aliphatic polythiol compounds include pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(thioglycolate), dipentaerythritol hexakis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptobutyrate), 1,3,4,6-tetrakis(2-mercaptoethyl)-1,3,4,6-tetraazaoctahydropentalene-2,5-dione, 1,3,5-tris(3-mercaptopropyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 4,8-, 4,7- or 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 1,3,4,6-tetrakis(2-mercaptoethyl) glycoluril, 1,2,3-tris(mercaptomethylthio)propane, 1,2,3-tris(2-mercaptoethylthio)propane, 1,2,3-tris(3-mercaptopropylthio)propane, 4-mercaptomethyl-1,8-dimercapto-3,6-dithiaoctane, 5,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,7-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, 4,8-dimercaptomethyl-1,11-dimercapto-3,6,9-trithiaundecane, tetrakis(mercaptomethylthiomethyl)methane, tetrakis(2-mercaptoethylthiomethyl)methane, tetrakis(3-mercaptopropylthiomethyl)methane, 1,1,3,3-tetrakis(mercaptomethylthio)propane, 1,1,2,2-tetrakis(mercaptomethylthio)ethane, 4,6-bis(mercaptomethylthio)-1,3-dithiane, 1,1,5,5-tetrakis(mercaptomethylthio)-3-thiapentane, 1,1,6,6-tetrakis(mercaptomethylthio)-3,4-dithiahexane, 2,2-bis(mercaptomethylthio)ethanethiol, 3-mercaptomethylthio-1,7-dimercapto-2,6-dithiaheptane, 3,6-bis(mercaptomethylthio)-1,9-dimercapto-2,5,8-trithianonane, 3-mercaptomethylthio-1,6-dimercapto-2,5-dithiahexane, 1,1,9,9 - Tetrakis(mercaptomethylthio)-5-(3,3-bis(mercaptomethylthio)-1-thiapropyl)3,7-dithianonane, Tris(2,2-bis(mercaptomethylthio)ethyl)methane, Tris(4,4-bis(mercaptomethylthio)-2-thiabutyl)methane, Tetrakis(2,2-bis(mercaptomethylthio)ethyl)methane, Tetrakis(4,4-bis(mercaptomethylthio)-2-thiabutyl)methane, 3,5,9,11-Tetrakis(mercaptomethylthio)-1,13-dimercapto-2,6,8,12-tetrathiadecane, 3,5,9,11,15,17-Hexakis(mercaptomethylthio)-1,19-dimercapto-2,6,8,12,14,18-hexathianonadecane, 9-(2,2-bis(mercaptomethylthio)ethyl)-3,5,13,15-tetrakis(mercaptomethylthio)-1,17-dimercapto-2,6,8,10,12,16-hexathiaheptadecane, 3,4,8,9-Tetrakis(mercaptomethylthio)-1,11-dimercapto-2,5,7,10-tetrathioundecane, 3,4,8,9,13,14-Hexakis(mercaptomethylthio)-1,16-dimercapto-2,5,7,10,12,15-hexathiahexadecane, 8-[Bis(mercaptomethylthio)methyl]-3,4,12,13-tetrakis(mercaptomethylthio)-1,15-dimercapto-2,5,7,9,11,14-hexathiapentadecane, 4,6-Bis[3,5-bis(mercaptomethylthio)-7-mercapto-2,6-dithiaheptylthio]-1,3-dithiane, 4-[3,5-bis(mercaptomethylthio)-7-mercapto-2,6-dithiaheptylthio]-6-mercaptomethylthio-1,3-dithiane, 1,1-Bis[4-(6-mercaptomethylthio)-1,3-dithianylthio]-1,3-bis(mercaptomethylthio)propane, 1-[4-(6-mercaptomethylthio)-1,3-dithianylthio]-3-[2,2-bis(mercaptomethylthio)ethyl]-7,9-bis(mercaptomethylthio)-2,4,6,10-tetrathioundecane, 1,5-Bis[4-(6-mercaptomethylthio)-1,3-dithianylthio]-3-[2-(1,3-dithietanyl)]methyl-2,4-dithiapentane, 3-[2-(1,3-[2-(1,3-dithietanyl)]methyl-7,9-bis(mercaptomethylthio)-1,11-dimercapto-2,4,6,10-tetrathioundecane, 9-[2-(1,3-dithietanyl)]methyl-3,5,13,15-tetrakis(mercaptomethylthio)-1,17-dimercapto-2,6,8,10,12,16-hexathiheptadecane, 3-[2-(1,3-dithietanyl)]methyl-7,9,13,15-tetrakis(mercaptomethylthio)-1,17-dimercapto-2,4,6,10,12,16-hexathiheptadecane, and 3,7-bis[2-(1,3-dithietanyl)]methyl-1,9-dimercapto-2,4,6,8-tetrathianonane, etc. are included.,

[0103] Examples of other polythiol furniture items include 4,6-bis{3-[2-(1,3-dithietanyl)]methyl-5-mercapto-2,4-dithiapentylthio}-1,3-dithiane, 4,6-bis[4-(6-mercaptomethylthio)-1,3-dithianylthio]-6-[4-(6-mercaptomethylthio)-1,3-dithianylthio]-1,3-dithiane, 4-[3,4,8,9-tetrakis(mercaptomethylthio)-11-mercapto-2,5,7,10-tetrathiaundecyl]-5-mercaptomethylthio-1,3-dithiolane, 4,5-bis[3,4-bis(mercaptomethylthio)-6-mercapto-2,5-dithiahexylthio]-1,3-dithiolane, 4-[3,4-bis(mercaptomethylthio)-6-mercapto-2,5-dithiahexylthio]-5-mercaptomethylthio-1,3-dithiolane, 4-[3-bis(mercaptomethylthio)methyl-5,6-bis(mercaptomethylthio)-8-mercapto-2,4,7-trithiaoctyl]-5-mercaptomethylthio-1,3-dithiolane, 2-{bis[3,4-bis(mercaptomethylthio)-6-mercapto-2,5-dithiahexylthio]methyl}-1,3-dithietane, 2-[3,4-bis(mercaptomethylthio)-6-mercapto-2,5-dithiahexylthio]mercaptomethylthiomethyl-1,3-dithietane, 2-[3,4,8,9-tetrakis(mercaptomethylthio)-11-mercapto-2,5,7,10-tetrathiaundecylthio]mercaptomethylthiomethyl-1,3-dithietane, 2-[3-bis(mercaptomethylthio)methyl-5,6-bis(mercaptomethylthio)-8-mercapto-2,4,7-trithiaoctyl]mercaptomethylthiomethyl-1,3-dithietane, 4,5-bis{1-[2-(1,3-dithietanyl)]-3-mercapto-2-thiapropylthio}-1,3-dithiolane, 4-{1-[2-(1,3-dithietanyl)]-3-mercapto-2-thiapropylthio}-5-[1,2-bis(mercaptomethylthio)-4-mercapto-3-thiabutylthio]-1,3-dithiolane, 2-{bis[4-(5-mercaptomethylthio-1,3-dithiolanyl)thio]methyl}-1,3-dithietane, and 4-[4-(5-mercaptomethylthio-1,It includes 3-dithiolanyl)thio]-5-{1-[2-(1,3-dithietanyl)]-3-mercapto-2-thiapropylthio}-1,3-dithiolane, etc.

[0104] From the viewpoint of enhancing the durability of the resin part when repeatedly discharging high-alcohol-concentration ink, the polythiol compound preferably has 4 or more thiol groups. More preferably, it has 6 or more thiol groups. The upper limit of the number of thiol groups is not particularly limited, but it can be 10 or less, and preferably 6 or less. Also, the more the number of thiol groups the polythiol compound has, the easier it is to achieve a good balance between the storage stability and curability of the composition when it is a one-component composition. However, the composition is not limited to a one-component composition, and it may be a two-component composition in which a liquid containing an episulfide resin and an epoxy resin and a liquid containing a polythiol compound are separated. Further, it may be a three-component composition in which a liquid containing an episulfide resin, a liquid containing an epoxy resin, and a liquid containing a polythiol compound are separated.

[0105] (Ratio by amount) The above-mentioned episulfide resin, epoxy resin, and polythiol compound can be used in any ratio.

[0106] The amount of the polythiol compound in the composition can be 0.2 equivalent or more and 2.0 equivalents or less, preferably 0.8 equivalent or more and 1.2 equivalents or less, and more preferably 0.9 equivalent or more and 1.1 equivalents or less, relative to 1 equivalent of the epoxy resin. When the amount of the polythiol compound is 0.2 equivalent or more, the curability of the composition is enhanced. When the amount of the polythiol compound is 2.0 equivalents or less, the heat resistance and durability, etc., are enhanced.

[0107] The amount of the episulfide resin in the composition can be 10 parts by mass or more and 300 parts by mass or less, preferably 20 parts by mass or more and 200 parts by mass or less, and more preferably 30 parts by mass or more and 150 parts by mass or less, based on 100 parts by mass of the total amount of the epoxy resin and the polythiol compound. When the amount of the episulfide resin is 10 parts by mass or more, swelling of the resin part by the high alcohol concentration ink can be more effectively suppressed. When the amount of the episulfide resin is 300 parts by mass or less, the durability of the resin part and the like are less likely to deteriorate.

[0108] (Curing catalyst) From the viewpoint of enhancing the durability of the resin part when discharging the high alcohol concentration ink repeatedly, the composition preferably contains a curing catalyst. Only one type of curing catalyst may be used, or two or more types may be used in combination.

[0109] Examples of the curing catalyst include phosphine compounds such as triphenylphosphine, phosphonium salts such as tetraphenylphosphonium bromide, imidazoles such as 2-methylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-undecylimidazole, 1-cyanoethyl-2-methylimidazole, 1-{3-[(3-trimethoxysilyl)propylaminocarbonylamino]propyl}-2-methylimidazole, 1-[3-trimethoxysilylpropylaminomethyl]-4-methylimidazole, 1-[3-(trimethoxysilylpropyl)]imidazole, 1-[3-(trimethoxysilylpropyl)]imidazole, and 1-benzyl-2-methylimidazole, imidazole salts which are salts of the above imidazoles with trimellitic acid, isocyanuric acid, boron, etc., amines such as benzyldimethylamine and 2,4,6-tris(dimethylaminomethyl)phenol, quaternary ammonium salts such as trimethylammonium chloride, ureas such as 3-(p-chlorophenyl)-1,1-dimethylurea, 3-(3,4-dichlorophenyl)-1,1-dimethylurea, 3-phenyl-1,1-dimethylurea, isophorone diisocyanate-dimethylurea, and tolylene diisocyanate-dimethylurea, complex compounds of boron trifluoride with amines, ether compounds, etc., polyepoxy compounds or isocyanate adducts of amine compounds having one or more active hydrogens, and amine-based latent curing agents obtained by combining these with a phenol resin. Among these, imidazoles and amines are preferred.

[0110] The content of the curing catalyst in the composition can be 0.1% by mass or more and 10% by mass or less, preferably 0.2% by mass or more and 5.0% by mass or less, and more preferably 0.5% by mass or more and 3.0% by mass or less, based on the total amount of the resin components. The resin components mean curable resins such as episulfide resins and epoxy resins.

[0111] Examples of amine compounds having one or more active hydrogens that can provide the above amine-based latent curing agent include alkylene diamines such as ethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,3-diaminobutane, 1,4-diaminobutane, and hexamethylenediamine; polyalkyl polyamines such as diethylenetriamine, triethylenetriamine, and tetraethylenepentamine; alicyclic polyamines such as 1,4-diaminocyclohexane, 1,3-diaminocyclohexane, 1,3-diaminomethylcyclohexane, 1,2-diaminocyclohexane, 1,4-diamino-3,6-diethylcyclohexane, 4,4'-diaminodicyclohexylmethane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, 4,4'-diaminodicyclohexylpropane, bis(4-aminocyclohexyl)sulfone, 4,4'-diaminodicyclohexyl ether, 2,2'-dimethyl-4,4'-diaminodicyclohexylmethane, isophoronediamine, and norbornenediamine; aromatic polyamines such as m-xylylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diethyltoluenediamine, 1-methyl-3,5-diethyl-2,4-diaminobenzene, 1-methyl-3,5-diethyl-2,6-diaminobenzene, 1,3,5-triethyl-2,6-diaminobenzene, 3,3'-diethyl-4,4'-diaminodiphenylmethane, and 3,5,3',5'-tetramethyl-4,4'-diaminodiphenylmethane; guanamines such as benzoguanamine and acetoguanamine; imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-isopropylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 2-aminopropylimidazole; dihydrazides such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, suberic acid dihydrazide, azelaic acid dihydrazide, sebacic acid dihydrazide, and phthalic acid dihydrazide; N,N-dimethylaminoethylamine, N,N-Diethylaminoethylamine, N,N-Diisopropylaminoethylamine, N,N-Diallylaminoethylamine, N,N-Benzylmethylaminoethylamine, N,N-Dibenzylaminoethylamine, N,N-Cyclohexylmethylaminoethylamine, N,N-Dicyclohexylaminoethylamine, N-(2-Aminoethyl)pyrrolidine, N-(2-Aminoethyl)piperidine, N-(2-Aminoethyl)morpholine, N-(2-Aminoethyl)piperazine, N-(2-Aminoethyl)-N’-methylpiperazine, N,N-Dimethylaminopropylamine, N,N-Diethylaminopropylamine, N,N-Diisopropylaminopropylamine, N,N-Diallylaminopropylamine, N,N-Benzylmethylaminopropylamine, N,N-Dibenzylaminopropylamine, N,N-Cyclohexylmethylaminopropylamine, N,N-Dicyclohexylaminopropylamine, N-(3-Aminopropyl)pyrrolidine, N-(3-Aminopropyl)piperidine, N-(3-Aminopropyl)morpholine, N-(3-Aminopropyl)piperazine, N-(3-Aminopropyl)-N’-methylpiperidine, 4-(N,N-Dimethylamino)benzylamine, 4-(N,N-Diethylamino)benzylamine, 4-(N,N-Diisopropylamino)benzylamine, N,N,-Dimethylisophoronediamine, N,N-Dimethylbisaminocyclohexane, N,N,N’-Trimethylethylenediamine, N’-Ethyl-N,N-dimethylethylenediamine, N,N,N’-Trimethylethylenediamine, N’-Ethyl-N,N-dimethylpropanediamine, N’-Ethyl-N,N-dibenzylaminopropylamine; N,N-(Bisaminopropyl)-N-methylamine, N,N-Bisaminopropylethylamine, N,N-Bisaminopropylpropylamine, N,N-Bisaminopropylbutylamine, N,N-Bisaminopropylpentylamine, N,N-Bisaminopropylhexylamine, N,N-Bisaminopropyl-2-ethylhexylamine, N,N-Bisaminopropylcyclohexylamine, N,N-Bisaminopropylbenzylamine, N,N-Bisaminopropylallylamine, Bis[3-(N,N-Dimethylaminopropyl)]amine, Bis[3-(N,such as N-diethylaminopropyl)amine, bis[3-(N,N-diisopropylaminopropyl)]amine, bis[3-(N,N-dibutylaminopropyl)]amine, etc. are included.,

[0112] Examples of epoxy compounds capable of providing the above amine-based latent curing agent include polyglycidyl ether compounds of mononuclear polyhydric phenol compounds such as hydroquinone, resorcinol, pyrocatechol, and phloroglucinol; dihydroxynaphthalene, biphenol, methylenebisphenol (bisphenol F), methylenebis(orthocresol), ethylidenebisphenol, isopropylidenebisphenol (bisphenol A), isopropylidenebis(orthocresol), tetrabromobisphenol A, 1,3-bis(4-hydroxyt-butylbenzene), 1,4-bis(4-hydroxyt-butylbenzene), 1,1,3-tris(4-hydroxyphenyl)butane, 1,1,2,2-tetra(4-hydroxyphenyl)ethane, thiobisphenol, sulfonylbisphenol, oxybisphenol, phenol novolak, orthocresol novolak, ethylphenol novolak, butylphenol novolak, octylphenol novolak, resorcinol novolak, and terpene phenol; polyglycidyl ethers of polyhydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, hexanediol, polyglycol, thiodiglycol, glycerin, trimethylolpropane, pentaerythritol, sorbitol, and bisphenol A-alkylene oxide adducts; glycidyl esters of aliphatic, aromatic, or alicyclic polybasic acids such as maleic acid, fumaric acid, itaconic acid, succinic acid, glutaric acid, suberic acid, adipic acid, azelaic acid, sebacic acid, dimer acid, trimer acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, trimesic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid, and endomethylenetetrahydrophthalic acid; homopolymers or copolymers of glycidyl methacrylate; epoxy compounds having glycidylamino groups such as N,N-diglycidylaniline, bis(4-(N-methyl-N-glycidylamino)phenyl)methane, and diglycidyl orthotoluidine; vinylcyclohexene diepoxide, dicyclopentadiene diepoxide, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 3,Epoxides of cyclic olefin compounds such as 4-epoxy-6-methylcyclohexylmethyl 6-methylcyclohexanecarboxylate and bis(3,4-epoxy-6-methylcyclohexylmethyl) adipate, epoxidized conjugated diene polymers such as epoxidized polybutadiene and epoxidized styrene-butadiene copolymer, and heterocyclic compounds such as triglycidyl isocyanurate are included.,

[0113] Examples of polyisocyanate compounds capable of providing the above amine-based latent curing agents include aromatic diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, phenylene diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, 1,5-naphthylene diisocyanate, 1,5-tetrahydronaphthalene diisocyanate, 3,3'-dimethyldiphenyl-4,4'-diisocyanate, dianisidine diisocyanate, and tetramethylxylylene diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, trans-1,4-cyclohexyl diisocyanate, and norbornene diisocyanate; aliphatic diisocyanates such as tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4 and / or (2,4,4)-trimethylhexamethylene diisocyanate, and lysine diisocyanate; isocyanurate trimerization products, biuret trimerization products, and trimethylolpropane adducts of the above-exemplified diisocyanates; triphenylmethane triisocyanate, 1-methylbenzene-2,4,6-triisocyanate, and dimethyltriphenylmethane tetraisocyanate, etc. are included.,

[0114] These polyisocyanate compounds may be modified products such as carbodiimide modification, isocyanurate modification, and biuret modification, or may be blocked isocyanates blocked with various blocking agents.,

[0115] Examples of phenolic resins capable of providing the above amine-based latent curing agents include phenolic novolak resins, cresol novolak resins, aromatic hydrocarbon formaldehyde resin-modified phenolic resins, dicyclopentadiene phenol addition-type resins, phenol aralkyl resins (Zylok resins), naphthol aralkyl resins, trisphenylolmethane resins, tetraphenylethane resins, naphthol novolak resins, naphthol-phenol co-condensed novolak resins, naphthol-cresol co-condensed novolak resins, biphenyl-modified phenolic resins (polyhydric phenol compounds in which phenolic nuclei are linked by bismethylene groups), biphenyl-modified naphthol resins (polyhydric naphthol compounds in which phenolic nuclei are linked by bismethylene groups), aminotriazine-modified phenolic resins (compounds having a phenolic skeleton, a triazine ring, and a primary amino group in the molecular structure), and alkoxy group-containing aromatic ring-modified novolak resins (polyhydric phenol compounds in which a phenolic nucleus and an alkoxy group-containing aromatic ring are linked by formaldehyde), and other polyhydric phenol compounds.

[0116] (Other components) The composition may, if necessary, contain reactive or non-reactive diluents (plasticizers) such as monoglycidyl ethers, dioctyl phthalate, dibutyl phthalate, benzyl alcohol, and coal tar, fillers or pigments such as glass fiber, carbon fiber, cellulose, silica sand, cement, kaolin, clay, aluminum hydroxide, bentonite, talc, silica, fine powder silica, titanium dioxide, carbon black, graphite, iron oxide, and bituminous substances, lubricants such as candelilla wax, carnauba wax, wood wax, spermaceti wax, beeswax, lanolin, whale wax, montan wax, petroleum wax, fatty acid wax, fatty acid ester, fatty acid ether, aromatic ester, and aromatic ether, thickeners, thixotropic agents, antioxidants, light stabilizers, ultraviolet absorbers, flame retardants, defoamers, rust preventives, and known additives such as colloidal silica and colloidal alumina. Further, the composition may contain tacky resins such as xylene resins and petroleum resins.

[0117] (Method for manufacturing resin part) The resin part can be produced by applying a composition containing these materials and heating and curing it while applying a certain weight if necessary. The heating at this time can be carried out at 80°C or higher and 100°C or lower. The heating may be carried out for 1 hour or more and 4 hours or less.

[0118] (Thickness) The adhesive layer 210 (the joint part joining the nozzle plate 111 and the pressure chamber forming plate 112) as the resin part preferably has a thickness of 0.5 μm or more and 4.0 μm or less. By setting the thickness to 0.5 μm or more, the adhesive strength can be sufficiently increased, and ink leakage between nozzles can be suppressed. By setting the thickness to 4.0 μm or less, it is possible to make it difficult to generate nozzle defects due to the outflow of resin to the nozzles.

[0119] The adhesive layer 220 (the joint part joining the pressure chamber forming plate 112 and the drive plate 113) as the resin part preferably has a thickness of 0.1 μm or more and 2.5 μm or less. By setting the thickness to 0.1 μm or more, the adhesive strength can be sufficiently increased. By setting the thickness to 2.5 μm or less, the volume of the pressure chamber 57 can be made sufficiently large to sufficiently increase the ink discharge amount.

[0120] (Impregnation rate) These resin parts preferably have an impregnation rate of less than 4.0%, more preferably 3.8% or less, and even more preferably 3.7% or less when immersed in 100% ethanol for 2 weeks. The impregnation rate is the value shown in the following (1). Impregnation rate (%) = (Mass before TGA heating - Mass after TGA heating) / (Mass before TGA heating) × 100 (1)

[0121] More specifically, the impregnation rate is measured by the following method. The resin part cut from the head 55 is weighed and immersed in 100% ethanol, and stored in a sealed state at 60°C for one week. After one week, it is taken out from the solution, and TGA measurement is performed using a sample left for 1 hour at 22°C and 50% Rh. In the TGA measurement, the sample temperature is raised from 30°C to 100°C at 7°C / min and then held for 1 hour. The sample before and after heating is weighed, and the impregnation rate is calculated by the following formula. Impregnation rate = (Mass of the sample before TGA heating - Mass of the sample after TGA heating) / (Mass of the sample before TGA heating)

[0122] These resin parts (adhesive layer 210 and adhesive layer 220) are arranged at least partially exposed in the ink flow path. And according to the findings of the present inventors, high-alcohol-concentration ink easily penetrates into the resin exposed in the flow path within the head 55. When these resin parts swell or dissolve due to the penetrated ink, deformation of the head 55 may occur, or stress may be locally concentrated and peeling may occur, resulting in defects such as nozzle defects. In particular, when the head 55 has a structure for circulating ink, since the ink always flows, swelling due to penetration into the resin part is likely to occur. Also, when using a shaking waveform when not discharging ink, since the ink always flows, swelling due to penetration into the resin part and the resulting defects are likely to occur.

[0123] On the other hand, the resin part obtained by curing a composition containing an episulfide resin and a thiol is less likely to swell even when it comes into contact with high-alcohol-concentration ink in the head 55. This is considered to be because an episulfide resin and a thiol compound react during curing to form a sulfide bond. Different from the oxide bond formed during the curing of an epoxy resin, the sulfide bond formed during the curing of an episulfide resin is less likely to form a hydrogen bond with the hydroxyl group of alcohol. Therefore, it is considered that the resin part formed from the above materials is less likely to have the ink penetrate and swell even when it comes into contact with high-alcohol-concentration ink. According to the findings of the present inventors, even when circulating the ink or using a shaking waveform, the above resin part is less likely to swell due to the ink and the resulting defects.

[0124] The adhesive layer 210 and the adhesive layer 220 may be resin parts formed from any one of the above materials, or both may be resin parts formed from the above materials. Further, resin parts that are at least partially exposed in the ink flow path other than these adhesive layers may be resin parts formed from the above materials. For example, an adhesive layer for joining other plates, an adhesive layer for joining the piezoelectric element 58 and the diaphragm 57C, an adhesive layer for joining substrates when forming the manifold 56 by joining substrates, and an adhesive layer for joining the main body of the head chip 110 and the cap receiving plate that covers the lower surface thereof while exposing the nozzles may be resin parts formed from the above materials.

[0125] [Ink] The ink contains, as a solvent component, an alcohol having 1 to 4 carbon atoms in an amount of 60% by mass or more and 95% by mass or less based on the total mass of the ink. Such ink is excellent in quick-drying property. The amount of the alcohol having 1 to 4 carbon atoms in the ink is preferably 70% by mass or more and 95% by mass or less.

[0126] The alcohol having 1 to 4 carbon atoms includes methanol, ethanol, 1-propanol, 2-propanol (isopropyl alcohol), 1-butanol, isobutanol, 2-methyl-1-propanol (isobutyl alcohol), 2-butanol (sec-butyl alcohol), and 2-methyl-2-propanol (tert-butyl alcohol). Among these, methanol, ethanol, 1-propanol, and 2-propanol are preferred.

[0127] Among the alcohols having 1 to 4 carbon atoms, ethanol is more preferable because it has high quick-drying property and high safety, and thus environmental equipment is not required. At this time, only ethanol may be used as the solvent component, or ethanol and other alcohols having 1 to 4 carbon atoms may be used in combination. When the ink contains a phenolic resin or a terpene phenolic resin described later as the tackifier, in order to enhance the solubility of these resins, it is preferable to use 1-propanol or 1-butanol in combination with ethanol. From these viewpoints, the amount of ethanol in the ink is preferably 30% by mass or more and 95% by mass or less, and more preferably 30% by mass or more and 50% by mass or less. In addition, if the amount has a negligible effect on the human body, a small amount of 2-propanol or the like may be used.

[0128] The ink may contain a solvent component other than the alcohol having 1 to 4 carbon atoms. From the viewpoint of enhancing the solubility of the ink, these solvent components preferably have a boiling point of 120°C or higher. On the other hand, from the viewpoint of sufficiently enhancing the quick-drying property of the ink, it is preferable not to use too much of the solvent having a boiling point of 120°C or higher. Therefore, the amount of the solvent component other than the alcohol in the ink is preferably 0% by mass or more and 25% by mass or less, and more preferably 0% by mass or more and 15% by mass or less.

[0129] The ink preferably contains a phenolic resin in order to enhance the adhesion to a low-polarity medium such as a film. Only one type of phenolic resin may be used, or two or more types may be used in combination. Further, since the phenolic resin is thermoplastic and easily enhances the adhesiveness, it is preferably a novolak resin. Further, from the viewpoint of enhancing the adhesiveness, the phenolic resin preferably has a softening point of 70°C or higher and 125°C or lower, more preferably 80°C or higher and 120°C or lower, and even more preferably 90°C or higher and 110°C or lower. The softening point of the phenolic resin is the arithmetic mean value of the upper limit value and the lower limit value of the Vicat softening temperature (VST) measured according to JIS K7206:1997.

[0130] The amount of the phenolic resin in the ink is preferably 2% by mass or more and 20% by mass or less, more preferably 3% by mass or more and 15% by mass or less, and even more preferably 3% by mass or more and 8% by mass or less.

[0131] The ink may contain tackifiers such as terpene phenolic resins and rosin ester resins.

[0132] Further, the ink may contain known dyes or pigments, binder resins, surfactants, lubricants, and the like.

[0133] Such ink is likely to soak into the resin part in the head and swell the resin part. However, in this embodiment, since the head having the resin part described above is used, swelling of the resin part due to the above ink hardly occurs.

[0134] As described above, the embodiments of the present invention have been specifically described, but the present invention is not limited to the specific embodiments described above. Various modifications and changes can be made to the specific examples described in the above embodiments within the scope of the gist of the present invention described in the claims.

Examples

[0135] The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

[0136] 1. Production of Inkjet Head As the main component of the adhesive, episulfide resin (episulfide) having the structure shown in the following (10), aminophenol type epoxy resin (epoxy 1) having the structure shown in the following (11), phenol novolac type epoxy resin (epoxy 2) having the structure shown in the following (12), and bisphenol F type epoxy resin (epoxy 3) having the structure shown in the following (13) were prepared.

[0137]

Chemical formula

[0138]

Chem.

[0139]

Chem.

[0140]

Chem.

[0141] As polythiol compounds, pentaerythritol tetrakis(3-mercaptopropionate) (polythiol 1), dipentaerythritol hexakis(3-mercaptopropionate) (polythiol 2), and tris-[(3-mercaptopropionyloxy)-ethyl]-isocyanurate (polythiol 3) were prepared.

[0142] As curing catalysts, 1-benzyl-2-methylimidazole (curing catalyst 1) and N-benzyldimethylamine (curing catalyst 2) were prepared.

[0143] A nozzle plate made of SUS304, a pressure chamber forming plate made of SUS304, and a metal drive plate (diaphragm) containing Ni with a piezoelectric element and electrodes attached were prepared.

[0144] The above-mentioned materials were mixed while being cooled to form a resin composition. The resin composition was applied to the position where the pressure chamber forming plate of the nozzle plate with the surface washed was placed so that the thickness after curing would be 2.0 μm. Then, the pressure chamber forming plate was brought into contact with the applied resin composition and heated to 90°C. After 4 hours, it was confirmed that the resin composition had cured to form an adhesive layer and the pressure chamber forming plate was adhered to the nozzle plate.

[0145] Also, it was applied to the position where the pressure chamber forming plate of the drive plate with the surface cleaned so that the thickness after curing would be 1.5 μm. Then, the side of the pressure chamber forming plate where the nozzle plate was adhered to the applied resin composition was brought into contact with the side opposite to the nozzle plate, and it was heated to 90°C. After 3 hours, it was confirmed that an adhesive layer in which the resin composition was cured was formed and the pressure chamber forming plate was adhered to the nozzle plate.

[0146] The joined body in which the nozzle plate, the pressure chamber forming plate, and the drive plate obtained in this way were adhered was used as a simulated inkjet head.

[0147] 2. Preparation of Ink As materials for the ink, ethanol, 1-butanol, propylene glycol monoethyl ether (a solvent with a boiling point of 120°C or higher), solvent black 29 (dye), phenolite TD-2131 (softening point VT (°C) = 80°C) (phenolic resin) manufactured by DIC Corporation, which is a novolak resin, and phenolite TD-2090 (softening point VT (°C) = 120°C) (phenolic resin) manufactured by DIC Corporation, which is a novolak resin, were prepared.

[0148] These were mixed at the ratios shown in Table 1 to obtain Inks 1 to 3. The values in the table are in mass%.

[0149]

Table 1

[0150] 3. Evaluation 3-1. Durability The above ink was filled into the flow path of the fabricated inkjet head and stored in a thermostat maintained at 60°C. One month, two months, and three months after the start of storage, wiring was connected to the piezoelectric element of the inkjet head to eject the ink, and it was evaluated according to the following criteria. A: Even after storage for 3 months, there were no nozzles with ejection defects. B: There was no nozzle with injection defects until after 2 months of storage, but nozzles with injection defects occurred after 3 months of storage. C: There was no nozzle with injection defects until after 1 month of storage, but nozzles with injection defects occurred after 2 months of storage. D: Nozzles with injection defects occurred after 1 month of storage.

[0151] 3-2. Impregnation rate After peeling off the nozzle plate of the inkjet head, 5 mg of the adhering adhesive was scraped off. The scraped adhesive was weighed and immersed in 100% ethanol, and stored in a sealed state at 60 °C for 2 weeks. After 2 weeks, the sample taken out from the solution and dried for 1 hour was used for TGA measurement. In the TGA measurement, the sample temperature was raised from 30 °C to 100 °C at 7 °C / min and then held for 1 hour. The samples before and after heating were weighed, and the impregnation rate was calculated by the following formula. Impregnation rate = (Mass of the sample before TGA heating - Mass of the sample after TGA heating) / (Mass of the sample before TGA heating)

[0152] Based on the calculated impregnation rate, the evaluation was carried out according to the following criteria. A: The impregnation rate is less than 4.0%. B: The impregnation rate is 4.0% or more.

[0153] 3-3. Quick-drying property Using an inkjet head (manufactured by Konica Minolta, KM1024i) and an evaluation machine, inks 1 to 3 were ejected to print on the surface of a nylon film, and after pressing with paper (manufactured by EPSON, KA4100PSKR) 10 seconds later, it was pulled apart. The state of color transfer to the paper was observed and evaluated according to the following criteria. A: There was no color transfer to the paper. Also, no influence on printing was observed. B: Slight color transfer to the paper was observed, but no influence on printing was observed. C: There was significant color transfer to the paper, and an influence on printing was also observed.

[0154] Table 2 shows the resin composition used for manufacturing the inkjet head, the types of inks, and the evaluation results.

[0155]

Table 2

[0156] As shown in Table 2, an inkjet head containing a cured product of a composition containing an episulfide resin and a polythiol compound in the resin part was less likely to cause swelling of the resin part due to a high alcohol concentration.

[0157] This application claims the priority of Japanese Patent Application No. 2024-078101 filed on May 13, 2024. The matters described in the specification, claims, and drawings of the application at the time of filing are incorporated herein by reference.

Industrial Applicability

[0158] The present invention can achieve both quick-drying properties with high alcohol concentration inks and the durability of the inkjet head.

Explanation of Signs

[0159] 1 Inkjet printer 10 Conveying unit 11 Conveyor belt 11a Conveying surface 12 Driving roller 13 Driven roller 20 Supply unit 21 Storage unit 22 Unwinding roller 30 Discharge unit 31 Storage unit 32 Take-up roller 40 Ink supply unit 41 Main tank 42 Flow path 50 Drawing unit 51 Carriage 52a First sub-tank 52b Second sub-tank Flow paths 53a, 53b, 53c 54 Head drive unit 55 Inkjet head 56 Manifold (common supply flow path) 57 Pressure chamber 57a, 57b Partition walls 57c Diaphragm 58 Piezoelectric element 59 Nozzle 60 Reading unit 70 Operation display unit 80 Input / output interface 90 Control unit 91 CPU 92 RAM 93 ROM 94 Storage unit 95 Drying unit 99 External device 101 Housing 102 Exterior member 103a Inlet 103b, 103c Outlets 104 Mounting hole 110 Head chip 111 Nozzle plate 111a Liquid-repellent film 112 Pressure chamber forming plate 112a Common supply flow path 112b Individual supply flow path 112c Vertical supply flow path 112d Common discharge flow path 112e Individual discharge flow path 112f Vertical discharge flow path 113 Driving plate 113a Space part 113c Vertical supply flow path 113f Vertical discharge flow path 114 Housing part 210, 220 Adhesive layers

Claims

1. A method for forming an image by ejecting ink from an inkjet head, comprising the steps of: the inkjet head has an ink flow path and a resin portion at least partially exposed to the ink flow path, the resin portion includes a cured product of a composition including an episulfide resin and a polythiol compound, the ink contains an alcohol having 1 to 4 carbon atoms in an amount of 60% by mass to 95% by mass with respect to the total mass of the ink; Image forming method.

2. The ink contains ethanol in an amount of 30% by mass or more based on the total mass of the ink. The image forming method according to claim 1 .

3. The resin portion is a cured product of a composition further containing a curing catalyst. The image forming method according to claim 1 .

4. The curing catalyst comprises an amine or an imidazole. The image forming method according to claim 3.

5. The cured product is immersed in 100% ethanol in a 60°C environment for 2 weeks, and then the sample temperature is raised from 30°C to 100°C at a rate of 7°C / min. After that, TGA measurement is performed by holding the sample for 1 hour. The impregnation rate is calculated from the mass of the cured product by the following formula (1) of less than 4.0%. The image forming method according to claim 1 . Impregnation rate (%) = (mass before TGA heating - mass after TGA heating) / (mass before TGA heating) x 100 (1)

6. The polythiol compound is a compound having four or more thiol groups. The image forming method according to claim 1 .

7. The resin portion is a joining portion that joins the vibration plate and the pressure chamber forming substrate. The image forming method according to claim 1 .

8. The resin portion has a thickness of 0.1 μm or more and 2.5 μm or less. The image forming method according to claim 7.

9. the resin portion is a bonding portion that bonds the nozzle plate and the pressure chamber forming substrate; The image forming method according to claim 1 .

10. The resin portion has a thickness of 0.5 μm or more and 4.0 μm or less. The image forming method according to claim 9.

11. the inkjet head circulates the ink for each nozzle that ejects the ink; The image forming method according to claim 1 .

12. the inkjet head causes the ink to flow by a vibration waveform when the ink is not being ejected; The image forming method according to claim 1 .

13. Forming an image on a recording medium transported by roll-to-roll; The image forming method according to claim 1 .

Images